ICMP message-routing gossip (#304)

* core logic for ICMP gossip

* refactor gossip to make more extension friendly

* move files aroun

* extract attestation-gossip logic to its own module

* message validation and broadcast logic

* fix upstream crates' compilation

* add a test

* another test for overlapping

* Some grammar and phrasing tweaks

Co-Authored-By: Luke Schoen <ltfschoen@users.noreply.github.com>

* add since parameter to ingress runtime API

* broadcast out known unrouted message queues

* fix compilation of service and collator

* remove useless index_mapping

* some tests for icmp propagation

* fix decoding bug and test icmp queue validation

* simplify engine-id definition

Co-Authored-By: Sergei Pepyakin <sergei@parity.io>

* address some grumbles

* some cleanup of old circulation code

* give network a handle to extrinsic store on startup

* an honest collator ensures data available as well

* address some grumbles

* add docs; rename the attestation session to "leaf work"

* module docs

* move gossip back to gossip.rs

* clean up and document attestation-gossip a bit

* some more docs on the availability store

* store all outgoing message queues in the availability store

* filter `Extrinsic` out of validation crate

* expunge Extrinsic from network

* expunge Extrinsic from erasure-coding

* expunge Extrinsic from collator

* expunge from adder-collator

* rename ExtrinsicStore to AvailabilityStore everywhere

* annotate and clean up message-routing tests

polkadot/erasure-coding/src/lib.rs

@@ -27,7 +27,7 @@
 use codec::{Encode, Decode};
 use reed_solomon::galois_16::{self, ReedSolomon};
 use primitives::{Hash as H256, BlakeTwo256, HashT};
-use primitives::parachain::{BlockData, Extrinsic};
+use primitives::parachain::{BlockData, OutgoingMessages};
 use substrate_primitives::Blake2Hasher;
 use trie::{EMPTY_PREFIX, MemoryDB, Trie, TrieMut, trie_types::{TrieDBMut, TrieDB}};
 
@@ -124,11 +124,11 @@ fn code_params(n_validators: usize) -> Result<CodeParams, Error> {
 /// Obtain erasure-coded chunks, one for each validator.
 ///
 /// Works only up to 65536 validators, and `n_validators` must be non-zero.
-pub fn obtain_chunks(n_validators: usize, block_data: &BlockData, extrinsic: &Extrinsic)
+pub fn obtain_chunks(n_validators: usize, block_data: &BlockData, outgoing: &OutgoingMessages)
 	-> Result<Vec<Vec<u8>>, Error>
 {
 	let params  = code_params(n_validators)?;
-	let encoded = (block_data, extrinsic).encode();
+	let encoded = (block_data, outgoing).encode();
 
 	if encoded.is_empty() {
 		return Err(Error::BadPayload);
@@ -150,7 +150,7 @@ pub fn obtain_chunks(n_validators: usize, block_data: &BlockData, extrinsic: &Ex
 ///
 /// Works only up to 65536 validators, and `n_validators` must be non-zero.
 pub fn reconstruct<'a, I: 'a>(n_validators: usize, chunks: I)
-	-> Result<(BlockData, Extrinsic), Error>
+	-> Result<(BlockData, OutgoingMessages), Error>
 	where I: IntoIterator<Item=(&'a [u8], usize)>
 {
 	let params = code_params(n_validators)?;
@@ -399,7 +399,7 @@ mod tests {
     #[test]
 	fn round_trip_block_data() {
 		let block_data = BlockData((0..255).collect());
-		let ex = Extrinsic { outgoing_messages: Vec::new() };
+		let ex = OutgoingMessages { outgoing_messages: Vec::new() };
 		let chunks = obtain_chunks(
 			10,
 			&block_data,
@@ -428,7 +428,7 @@ mod tests {
 		let chunks = obtain_chunks(
 			10,
 			&block_data,
-			&Extrinsic { outgoing_messages: Vec::new() },
+			&OutgoingMessages { outgoing_messages: Vec::new() },
 		).unwrap();
 		let chunks: Vec<_> = chunks.iter().map(|c| &c[..]).collect();